Academic journal article Transactions of the American Philosophical Society

Gregory Chioniades and Palaeologan Astronomy

Academic journal article Transactions of the American Philosophical Society

Gregory Chioniades and Palaeologan Astronomy

Article excerpt

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FOR almost seven centuries following the publication of the commentary on the Handy Tables of Theon by Stephanus of Alexandria1 little interest was shown in mathematical astronomy in Byzantium. It is tme that, in the ninth century, under the leadership of Leo the Mathematician,3 the text of Ptolemy's Almagest was studied and copied,3 and that scholars in the eleventh and twelfth centuries had learned something of Arabic science. But it seems improbable that many, save perhaps the astrologers, had the motivation or the training necessary for an attempt to understand more than the most elementary principles of the motions of the celestial spheres; and even the astrologers really needed nothing beyond an ability to manipulate tables.

This neglect continued into the thirteenth century, both at Nicaea and in Constantinople after it had been recovered from the Latins. But the beginnings of a revival of astronomical studies can be traced to the early decades of this century when a few scholars sought to sustain Greek learning under the patronage of John III Vatatzes (1222-1254) and Theodore II Lascaris (1254-1258).

Nicephorus Blemmydes,4 who taught at the Imperial court from 1238 to 1248 and whose pupils included George Acropolites,5 reawakened an interest in ancient Greek science which had been virtually dead since the time of Michael Psellos8 in the eleventh century. His Epitome physica7 is a completely unoriginal book, and its treatment of astronomy (chapters 25-30) is pitifully inadequate. He has very little that is sensible to say about planetary theory ; but he does demonstrate that he has read Aristotle, Cleomedes, and Euclid with some comprehension, and he observed at least one lunar eclipse, that of 18 May 1258.8

An account9 of an observation of a solar eclipse by his pupil George Acropolites in the company of the Imperial court on 3 June 1239 reveals the intellectual atmosphere in which Nicephorus was working. The Empress Irene asked Acropolites, then only twenty-one years old, what had caused this phenomenon. He, though he had just begun his studies under Blemmydes, was able to reply correctly that the Moon was interposed between the Earth and the Sun. The court physician, Nicolaus, scoffed at this ridiculous response, and the Empress, trusting her doctor, called Acropolites a fool. She quickly regretted her use of this derogatory term, not because she realized the correctness of Acropolites' explanation, but because she considered it improper to insult one engaged in philosophical studies. Two years later the Empress died; the philosopher seriously suggests that the eclipse was a portent of that unfortunate event, as was also the appearance of a bearded comet. It was Acropolites who, after the capture of Constantinople by Michael VIII Palaeologus in 1261, restored mathematics to the capital; he taught Euclid and Nicomachus to George (later Gregory) of Cyprus and others.10

Among his pupils was, apparently, George Pachymeres,11 a man who progressed much further in astronomical studies than had his teacher. Pachymeres' knowledge of this subject is, naturally, set forth in the fourth book of his Quadrivium.12 To a large extent this consists of elaborate instructions for the multiplication of sexagesimal numbers, a procedure he regarded as incredibly difficult, a discussion of the risings, settings, and culminations of various constellations, and a number of the fundamental doctrines of astrology, many of which are also found in the Epitome physica of his mentor's mentor. He is capable of such improbable statements as: "They say that a yearly revolution of the Sun takes place in 365 degrees (poipais for finipcuç), 14 minutes, and 48 seconds" ; but his planetary theory is far more complete than that of his predecessor, and he himself is far from being confused about everything.

George of Cyprus' friend John Pediasimus13 continued Blemmydes' study of Cleomedes' KvkAikí) eecopia pmcbpcov, on which he wrote a commentary ; and other mathematicians of this period were Maximus Planudes,14 who composed one of the first treatises on Indian numerals in Byzantium15 and an exegesis of the first two books of Diophantus,16 and his pupil Manuel Moschopulus, who wrote the first Western treatise on the construction of magic squares. …

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